Pass host to DD, not hostname

Hi!

It seems that passing hostname to Datadog doesn't get translated into host on their end.

See this screenshot where hostname is passed in the data object of the log, but not shown in the log entry - it says simons-mbp-2.lan.

For the other log I have applied my change in this PR, and we can see that host in the log entry corresponds to what I sent as host in the data object:

In order to not break the API, we can still have hostname parameter untouched, but also allow it to be host to align with Datadog's naming.

This is the test output. Please advise if you want it in any other format.

# simonauner at simons-mbp-2.lan in ~/code/pino-datadog on git:rename-hostname-to-host ✖︎ [12:21:35]
→ npm test

> pino-datadog@2.0.2 test /Users/simonauner/code/pino-datadog
> standard && tap test/*.test.js --coverage --100

 PASS  test/streams.test.js 15 OK 36.545ms
 PASS  test/index.test.js 2 OK 20.579ms
test/datadog.test.js 2> The previous log have not been saved
test/datadog.test.js 2> Error
test/datadog.test.js 2> Error: Error
test/datadog.test.js 2>     at Object.rejects (/Users/simonauner/code/pino-datadog/node_modules/sinon/lib/sinon/default-behaviors.js:193:22)
test/datadog.test.js 2>     at Object.proto.<computed> [as rejects] (/Users/simonauner/code/pino-datadog/node_modules/sinon/lib/sinon/behavior.js:238:12)
test/datadog.test.js 2>     at Function.<anonymous> (/Users/simonauner/code/pino-datadog/node_modules/sinon/lib/sinon/behavior.js:231:46)
test/datadog.test.js 2>     at Test.<anonymous> (/Users/simonauner/code/pino-datadog/test/datadog.test.js:19:46)
test/datadog.test.js 2>     at TapWrap.runInAsyncScope (async_hooks.js:197:9)
test/datadog.test.js 2>     at Test.cb (/Users/simonauner/code/pino-datadog/node_modules/tap/lib/test.js:147:40)
test/datadog.test.js 2>     at /Users/simonauner/code/pino-datadog/node_modules/tap/lib/test.js:385:21
test/datadog.test.js 2>     at Test.main (/Users/simonauner/code/pino-datadog/node_modules/tap/lib/test.js:392:7)
test/datadog.test.js 2>     at TapWrap.runInAsyncScope (async_hooks.js:197:9)
test/datadog.test.js 2>     at Test.runMain (/Users/simonauner/code/pino-datadog/node_modules/tap/lib/base.js:193:15)
 PASS  test/datadog.test.js 17 OK 56.717ms

  🌈 SUMMARY RESULTS 🌈  

Suites:   3 passed, 3 of 3 completed
Asserts:  34 passed, of 34
Time:     1s
------------|----------|----------|----------|----------|-------------------|
File        |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
------------|----------|----------|----------|----------|-------------------|
All files   |      100 |      100 |      100 |      100 |                   |
 datadog.js |      100 |      100 |      100 |      100 |                   |
 index.js   |      100 |      100 |      100 |      100 |                   |
 streams.js |      100 |      100 |      100 |      100 |                   |
------------|----------|----------|----------|----------|-------------------|

> pino-datadog@2.0.2 posttest /Users/simonauner/code/pino-datadog
> tap --coverage --coverage-report=lcovonly

Checklist

[x] run npm run test
[x] tests and/or benchmarks are included
[x] documentation is changed or added
[x] commit message and code follows Code Of Conduct

ovhemert / pino-datadog

Pass host to DD, not hostname #89

Checklist